Prelude

Water is composed of hydrogen and oxygen, that is essential for

the survival of many known forms of life . In typical usage, water refers only

to its liquid form or state, but the substance also has a solid state, ice, and

a gaseous state, water vapor or steam. Water covers 71% of the Earth's

surface. On Earth, it is found mostly in oceans and other large water bodies,

with 1.6% of water below ground in aquifers and 0.001% in the air

as vapor, clouds (formed of solid and liquid water particles suspended in

air). Oceans hold 97% of surface water and other land surface water such

as rivers, lakes and ponds 0.6%. A very small amount of the Earth's water is

contained within biological bodies and manufactured products. Water

moves continually through a cycle of evaporation reaching the sea.

Clean, fresh drinking water is essential to human and other life forms.

Access to safe drinking water has improved steadily and substantially over

the last decades in almost every part of the world. There is a clear

correlation between access to safe water and GDP per capita. However,

some observers have estimated that by 2025 more than half of the world

population will be facing water-based vulnerability. Water plays an

important role in the world economy, as it functions as a solvent for a wide

variety of chemical substances and facilitates industrial cooling and

transportation. Approximately 70 percent of freshwater is consumed

by agriculture.

Water Pollution

Water pollution is the contamination of water bodies such as lakes, rivers,

oceans, and groundwater. All water pollution affects organisms and plants

that live in these water bodies and in almost all cases the effect is damaging

either to individual species and populations but also to the

natural biological communities. It occurs when pollutants are discharged

directly or indirectly into water bodies without adequate treatment to

remove harmful constituents. Water is typically referred to as polluted when

it does not support a human use, like serving as drinking water, and lose its

ability to support its biotic communities, such as fish. Natural phenomena

such as volcanoes, algae blooms, storms, and earthquakes also cause major

changes in water quality and the ecological status of water. Water pollution

has many causes and characteristics.

Surface water and groundwater have often been studied and managed as

separate resources, although they are interrelated. Sources of surface

water pollution are generally grouped into two categories based on their

origin.

Point source pollution

Point source pollution refers to contaminants that enter a waterway through

a discrete conveyance, such as a pipe or ditch. Examples of sources in this

category include discharges from a sewage treatment plant, a factory, or a

city storm drain.

Non-point source pollution

Non-point source pollution refers to diffuse contamination that does not

originate from a single discrete source. NPS pollution is often accumulative

effect of small amounts of contaminants gathered from a large area. The

leaching out of nitrogen compounds from agricultural land which has been

fertilized is a typical example. Nutrient run off in storm water from "sheet

flow" over an agricultural field or a forest are also cited as examples of NPS

pollution.

Water Pollution in Dhaka City

Water pollution in Dhaka watershed has reached alarming levels and is

posing significant threats to health and economic activity, particularly

among the poor and vulnerable. With all the frequent power outages,

horrendous traffic jams and the like already complicating life in the city, the

shortage of water promises to create new nightmares for everyone. In most

large city areas -- notably Rampura, Kalyanpur, Shekher Tek and

Mohammadpur and old Dhaka -- citizens have been suffering from lack of

water for the past several days. Scarcity of water is so acute in several

areas that residents are now thinking of leaving those places. The problem

has become acute due to inadequate water supply and contaminated water.

A number of residents are now using contaminated water as the special

supply of water by the Water Supply and Sewerage Authority (WASA) is not

enough. People facing the crisis claimed the water supply by the WASA

Lorries hardly fulfills their daily demand.Rice productivity in the watershed

area, for example, has declined by 40% in recent years and vegetable

cultivation in the riverbeds has been severely damaged. Its also found

significant correlation between water pollution and diseases such as

jaundice, diarrhoea and skin problems.

The causes of water pollution in Dhaka city:

Excessive rainfall

Population growth and unplanned development

Waste management system

Encroachment

Capacity and gravity of drainage system

Drainage management system

Development works during rainy season

Storage of construction materials

Lack of public awareness

Lack of regulations and its implementation

Effects:

Disruption of normal life

Damage of household goods

Damage of underground service lines

Water born diseases

Increase mosquito

Damage of trees and vegetation

Increase of construction and maintenance cost

Death of fish

Conclusion

Experts say it is not environmentally and practically feasible to extract

ground water indiscriminately. It will not be possible to meet the growing

demand for water with ground water and that’s why main focus should be in

collecting river water no matter how costly it is. The wetlands around the

city should be protected from the grabbers and turned into water reservoirs

involving the water supply agency, Dhaka City Corporation, Rajdhani

Unnayan Kartripakkha, and environmentalists. Successful implementation

of such efforts will reduce the city's water crisis to a considerable extent.